Explanation:

We are given four numbers: $1260, 1156, 2601, 1849$. We need to find the odd one out. Let's examine if these numbers are perfect squares: A) $1260$: $\sqrt{1260} \approx 35.49$. This is not an integer, so $1260$ is not a perfect square. B) $1156$: $\sqrt{1156} = 34$. So, $1156$ is a perfect square ($34^2$). C) $2601$: $\sqrt{2601} = 51$. So, $2601$ is a perfect square ($51^2$). D) $1849$: $\sqrt{1849} = 43$. So, $1849$ is a perfect square ($43^2$). From this analysis, it is clear that $1156, 2601,$ and $1849$ are all perfect squares, while $1260$ is not. Therefore, $1260$ is the odd one out.